MUSCULOSKELTAL SYSTEM

Question 1

ARE ADULT BONES STABLE?

Answer 1

NO, THEY ARE NOT STABLE INERT MATERIAL.

Question 2

what are osteoblast cells in bones?

Answer 2

OSTEOBLASTS= BONE MAKERS produce bones, regenerates bones

Question 3

what are osteoclast cells in bones?

Answer 3

OSTEOCLASTS: BONE BREAKERS, breaks down bones into its minerals and removes damaged bones

Question 4

WHAT ARE OSTEOCYTES?

Answer 4

OSTEOCYTES ARE BONE MAINTAINERS: a mature bone cell, and they surround bones to protect them.

Question 5

what are bones made from?

Answer 5

calcium crystals (hydroxyapatite) in osteoid matrix

Question 6

how is the bone formed?

Answer 6

osteoblasts lay down osteoid.

calcification: the hardening of tissue by depositing calcium phosphate (hydroapatite)

Question 7

what happens when osteoblasts mature?

Answer 7

they become immobilised (stops operating)

osteocyte maintains surrounding osteoid

Question 8

how does bone resorption happen (breakdown from inner to outer bones and assimilation of old bone and laying of new bones cells)?

Answer 8

-osteoclasts secrete acid and enzymes
-acid dissolves calcium phosphate crystals
-enzymes degrade osteoid
-calcium and phosphate released from bone into blood

Question 9

how does bones grow when increasing in width?

Answer 9

-osteoblasts lay down new bone on outer surface
-osteoclasts resorb bone in inner surface of cavity to out

minimises weight gain

Question 10

how does bones grow when increasing in length?

Answer 10

osteoblasts lay down new bone at epiphyseal plate (end of shaft- long main part of bone)

Question 11

in detail what happens in the epiphyseal plate when bones increase in length? (4)

Answer 11

CHONDROCYTES PRODUCE NEW CARTILAGE in epiphyseal plate

epiphyseal plate widens causing bone to lengthen

chondrocytes die

osteoblasts replace chondrocytes and lay down bone

Question 12

when does epiphyseal plate closure happen?

Answer 12

at puberty:
girls: 13-15yrs
boys: 15-17 yrs

Question 13

what are the 3 effects of abnormal growth hormone (GH) secretion?

Answer 13

1. dwarfism
2. gigantism
3. acromegaly

Question 14

what is dwarfism?

Answer 14

decreased GH secretion in children

Question 15

what is gigantism?

Answer 15

increased GH secretion in children (pre-puberty)

Question 16

what is ACROMEGALY?

Answer 16

INCREASED GH SECRETION IN ADULTS (not taller bit affects the visual characteristics of person like jaw growth, long face.)

Question 17

what other hormones affect growth?

Answer 17

1. thyroid hormones : rewired for synthesis of GH
2. insulin: needed for cellular action of GH
3. sex hormones: important in pubertal growth.
4. Glucocortoids: inhibit growth, inhaler minimises effects of glucocortoids as not too much secreted at one go.

Question 18

what are two bone diseases?

Answer 18

osteomalacia (rickets in children)

osteoporosis (epidemic levels)

Question 19

what are 2 joint diseases?

Answer 19

1. osteoarthritis
2. gout

Question 20

what is osteomalacia (rickets)?

Answer 20

deficiency in bone mineralisation –> softening and weakening of bones

Question 21

what causes osteomalacia (rickets)?

Answer 21

dietary insufficiency (VITAMIN D2)

LACK OF SUNLIGHT (vitamin D3)

renal disease causing decreased calcitriol

Question 22

what can osteomalacia rickets be treated by?

Answer 22

vitamin D :

Ergocalciferol (type of vitamin D found in food)

Calcitriol - if renal disease (active form of vitamin D made in the kidney which binds to and activates vitamin D receptors)

Question 23

what causes osteoporosis?

Answer 23

-low bone density (loss of hydroxapatite)- from fall or incidence more likely for bones break more easily
-more common in elderly women

Question 24

who is at most risk of osteoporosis- low bone density

Answer 24

post menopausal women
over 75 yrs
glucocorticoid induced